BACKGROUNDTo study the correlation between CT/MRI features and surgical and pathological findings of cancerous invasion of the main pulmonary artery (CIMPA) in lung cancer and to evaluate the role of CT and MRI in making surgical plan.

METHODSCT findings in 15 cases and MRI findings in 13 cases were observed and blindly compared with surgical and pathological findings in this prospective study of 23 cases of central type lung cancer.

RESULTSThe CT and MRI features showed as follows: the wall thickening sign in 73.7% of CT and 84.6% of MRI; lumen narrowing sign in 55.3% of CT and 69.2% of MRI; peri-vascular fat sign in 100.0% of both CT and MRI. Two types of CIMPA were visualized: contacted type (10 cases in CT and 7 cases in MRI) and encased type (5 cases in CT and 6 cases in MRI). Surgically, contacted type was found in 10 cases who all underwent lobectomy with sleeve-angioplasty. Encased type was found in 13 cases, among whom unresectable in 2, pneumonectomy in 7, and lobectomy with angioplasty in 4. Of the 21 resected specimen, the cancerous infiltration was demonstrated 100.0% (21/21) in adventitia, 66.7% (14/21) in media and 4.8% (1/21) in intima. There was no significant difference in the deepness of the cancer infiltration between the two types (P>0.05). Acute or chronic inflammatory infiltration which enhanced the thickening of the wall were shown on all specimens. CT and MRI findings were well corresponding to surgical and pathological appearance (Kappa value = 0.61 in CT and 0.84 in MRI).

CONCLUSIONSIn our study of CIMPA, CT and MRI features characterized by wall thickening and lumen narrowing without occlusion are closely correlated with pathological findings that cancerous invasion prominently limited adventitia and media with remarkable proliferation of connective tissue, and classifying two types is valuable in making surgical plan.